Improvement in truss-bridges



WILLIAM JOHNSON, OF LAMBERTVILLE, NEW JERSEY.

Letters Patent No. 109,628, dated November 29, 1870.

' IMPROVEMENT IN TRUSS-BRIDGES.

The Schedule' referred to in these Letters Patent and making part of the same.

To all whom it may concern Be it known that I, WILLIAM JOHNSON, of the town of Lambertville, in the county of lIzIunterdon and State of New Jersey, have invented a new .and useful Improvement in Iron Bridges; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had tothe annexed drawing making a part of this specification.

My invention is applicable chiefly to iron bridgetrusses composed of, an upper and lower chord, diagonal rods, and upright posts, and is designed to obviatc the necessity for screw-nuts upon the diagonal rods, in order to adjust the bridge, substituting therefor eccentries, thereby insuring a greater degree of safety and also economy in the construction ol-` iron bridges.

1t is well known that nuts are liable to work ott' from screw-bolts, and to .the extent of such liability are a source ot danger; also, in point of' economy, where serew-nuts are used, the rods lnust be much larger than necessary to sustain the load, or the ends.

of the rods must be upset or enlarged for the nuts to compensate for the depth of the thread, which operation of upsetting is not only very expensive, but the quality ofthe iron is niore'or less injured thereby.

By the method here adopted, eyes are foi-ined at both en ds of the diagonal rods,.as.\v.ell.- as the lower chords; said eyes or loops pass around pins in the upper chord and foot of posts, the holes in said posts heilig of suiiicieut size to admit thc insertion of eceentrics around the pins. Said eccentrics are provided with notched iianges,liy means ot' which they are turned upon the pins.,

A lock or stop is employed to prevent the eccentrios in the posts from working buck when once the ,bridge is adjusted.

The counter diagouals lit upon .cccentrics on the pins by which they are tightened. Said eeceutricsare made with a loose. disk or .dan gc., through wh'ioli'aboltf passes, foi-fthe purposelof'clampingthe'eccentric.to` I the rod, and thereby prevent its worltiuglhack to loosen the rod.

In the accompanying drawing- Figure .1 is a face or front view of the upright post,

pin, eccentrics, stops, and diagonal rods, as seen from the end of the trussor bridge.

Figure 2 is an edge or side view of the same.

Figure 3 is a detached view of the eecentrics and stops attached to the upright posts.

Figure 4 shows the eccentric for counter diagonal.

llhe several letters in all the iigures referto the saine parts.

A is the upright post of truss.

1S, the pin.

E E, the eccentries in post.

S S, the locks or stops.

K, the eccentric for counter diagonal.

O O, main diagonal rods.

l), the counter diagonal rods.

11 li F are the bolts for securing eccentrics.

Ilhe operation is as follows:

The eccentrics passing through the posts and around the pins are iirst placed iu such position as to shorten the relative distance between the'upper' and lower chords, so as the more conveniently to get the' several parts together. `After the .truss is connected throughout, the post eccentrics are then turned to increase the distance between the upper and lower chords, thereby adjusting the truss in position and bringing an equal strain upon all the main diagonal rods. 'lhe lock-stops are then bolted to the posts, securing the eccentric-s firmly against any tendency they might have to move back and lower the truss. The counter diagonale are then adjusted to their proper bearing,'and secured by means of the eccentrics and bolts passing through them.

\Vhat I claim as lnyinvention, andl desire to secure by Letters Patent, is

l. The cccentrics E E aud K, in combination with post A, .piu B, and diagouals O O l), arranged in the manner and for the purpose, specified.

The lock-stops S S and'boI-ts'fhlh F, .when coinbined VandA arranged in the manner and for thepurpose substautiall y as described and set forth.

, WM. JOHNSON.

-Vtituesses: i

A. W. ANGEL,- O. W. ANGEL. 

